What is radical and how to pronounce it?

What is radical? Commonly known as "walking" or "walking" for short.

The words beside the word "Bi" are: Yi, Invitation, Jiong, Yi, Up to now, pedantic, sui, blending, pride, opposition, Yi, Yi, Yi, Yi. , _, _, _, _, legacy, _, Da, _, _, Jing, _, _, Nai, Gang, _, _, Zhou, _, _, _, curb, _